Biofilm vertical growth dynamics are captured by an active fluid framework

Area of Science:

• Microbiology
• Biophysics
• Fluid Dynamics

Background:

• Bacterial biofilms are surface-attached microbial communities exhibiting complex growth patterns.
• Existing heuristic models describe vertical biofilm growth but lack a clear theoretical basis.
• Understanding the biophysical drivers of biofilm architecture is crucial for controlling these communities.

Purpose of the Study:

• To investigate the theoretical underpinnings of empirical models for vertical bacterial biofilm growth.
• To develop a new, physically-grounded model for biofilm vertical expansion.
• To elucidate the role of cell death and decay in biofilm morphology.

Main Methods:

• Analytical derivation of solutions from an active fluid dynamics model for biofilm growth.
• Comparison of the derived model with existing heuristic models across different growth stages.
• Identification of key parameters influencing vertical growth rates and characteristic lengths.

Main Results:

• The heuristic model for vertical biofilm growth naturally emerges from active fluid dynamics principles.
• Cell death and decay rates are identified as critical factors in determining vertical growth parameters.
• A single, simpler equation governs biofilm growth at all heights, surpassing the complexity of heuristic models.
• The theoretical model explains maximum vertical growth rates at heights beyond previously defined scales.

Conclusions:

• Active fluid dynamics provides a robust theoretical foundation for understanding bacterial biofilm vertical growth.
• The new model offers a simplified and more accurate description of biofilm development.
• This work enhances the understanding of biological and biophysical interactions governing biofilm architecture.